Liquid expressing press



D United States Patent [111 3,548,743

[72], Inventor lo f- 772,230 /1904 Fame: 100/145X onklawmllll. 829,3158/1906 Andersom. 100/145 [21] AppLNo. 711,310 1,421,282 6/1922 Meakin100/150X [22] Filed Mar. 7, 1968 1,662,531 3/1928 Meakin 100/150Patented 1970 2,873,663 2/1959 Hawk et al..... 99/353 [73] AssigneeChemetron Corporation 829,314 8/1906 Anderson 100/117UX am 2,687,0848/1954 Bowman 100/117X aoorporationofDelaware 2,701,518 2/1955McDonald..... 100/117X 2,975,096 3/1961 Ginavenetal. 100/117 3,055,2919/1962 Ginaven 100/117 [54] LIQUID EXPRESSING PRESS FOREIGN PATENTScmmmmm' Figs 1,025,267 2/1958 Germany 100/145 [52] PrimaryExaminer-Walter A. Scheel Assistant Examiner-Leon G. Machlin [51] Int.B306 9/16 Field ofSearch /117, 4mm? Nchdas ABSTRACT: Apparatus having aperforate housing through [56] CM which liquid is expressed from aliquid-containing material by UNITED STATES PATENTS independentlyrotated screw conveyors that subject the 731,737 6/1903 Anderson100/145X material to varying pressures.

PATENTED DEB22 I970 SHEET 1 {1F 2 Inventor Jom-| H. PIKEL JH-korneg.

PATENTEDUECZZISYU I 3,548,743

sum 2 [IF 2 Inventor JOHN H. Pl KEL LIQUID EXPRESSING PRESS Thisinvention relates to apparatus for'materially increasing the density ofraw material solids which contain relatively large quantities of liquid,and is useful in a rendering process wherein otherwise undesirableanimal matters are used to make beneficial products including tallow:and edible, high protein meals. In particular the apparatus continuouslyand effectively handles cracklings from suet, fat, scraps, trimmings andinedible hard parts of animal bodies in the preparation of a proteinconcentrate which is used principally as feed for animals and fowl.

During rendering, the raw materials are ground or sized prior to cookingsince the raw material is more quickly rendered when it is cut uniformlyinto small pieces. In addition, less mechanical strain is placed on therendering equipment when these relatively small pieces are being movedduring the process than if randomly cut, large pieces are used. In acontinuous rendering process, reduced particle size is particularlyimportant for a practical minimum cooking time. Various pieces ofmachinery such as prebreakers, mills, grinders, hogs, and hashers, washand grind larger particles of the meat scraps and inedible hard parts ofanimals into relatively small, uniform portions. These ground and sizedparticles are blended in a surge tank fromwhich they are pumped into acooker for rendering by dehydration. During the rendering process thefatty animal tissue is broken down and lards, tal-. lows and greases arereleased in liquid form. Immediately after cooking, the cracklings aredeposited in percolating pans wherein some" of the liquid is drainedfrom the solids. These drained solids, called unpressed cracklings, aresupplied in a heated condition to the press of this invention whereinmost of the remaining liquid is expressed to produce pressed cracklings.Breakers are frequently used to reduce the pressed cracklings intorelatively small pieces which are easy to handle. Later these brokenpieces are ground into high protein meal which may be packaged forshipment. v

Available presses are inefficient and slow and frequently fines or smallparticles of the solid material are passed through the press with theliquid. Such particles plug up screens covering the drains. Some of thepresses produce a cake of solid, formed material which must be cooledprior to being broken up into a' more practical size for use as a meal.Known presses frequently require much hand labor and lost motion and inaddition much valuable storage space is required to hold the prasedcrackling material during cooling and prior to its being crushed.

This invention comprises a two-stage, horizontal conveyor in a perforateenclosure formed preferably as a slotted cylinder which expreses liquidfrom unpressed cracklings. A first section of the press containsahelicoidscrew conveyor which transports the liquid-containingcracklings along the enclosure so that some free liquid flows or drainsaway from the cracklings. The conveyor in the first section is driven ata speed which exceeds the product flow rate from a source such as acontinuous rendering cooker. By such an arrangement the cracklings arewidely distributed and agitatedwhile they are moved along in contactwith the perforate walls of the enclosure to provide efiicient liquiddrainage from the cracklings prior to their being received in a secondsection of the enclosure.

A helicoidal screw conveyor having flights with decreasingv pitch isrotatably mounted in the secondsection. The central shaft of thisvariable'pitch conveyor is relatively larger than the shaft of theconveyor in the first section and thus the crosssectional area withinthe slotted enclosure which is available to be occupied by thecracklings is abruptly decreased. In the illustrated embodiment, thecross-sectional area available to the cracklings in the second sectionof the apparatus is about one-fourth that available in the firstsection. The helicoid screw conveyor in the first section and thevariable pitch conveyor in the second section are each independentlydriven by an asociated prime mover such as a variable speed motor. Bydecreasing the volume displacement and pitch and reducing the rotationalspeed of the conveyor inthe second section, the

they emerge from the variable pitch screw conveyor.

It is the principal object of this inventionto provide a simple andefficient apparatus for increasingthe density of moisture containingmaterials.

A feature of this invention is to provide a worm assembly for use on arotatable shaft in a continuous press barrel wherein the worm flightarrangement and the rotational speed of the worm is such that a pressurebuild up efficiently expresses liquid products from and compacts amaterial which contained the products.

Another feature of this invention is to provide a grid cage assemblywhich produces effective grease extraction and provides large quantitiesof free grease which is substantially unaccompanied by fine pieces ofthe material being pressed.

An additional object of this invention is to provide an apparatus forcontinuously processing grease bearing materials to produce pressedcakes of the dried material which are reducible to a size that is easilyhandled. i

Yet another object of this invention is to provide apparatus for rapidlyand efficientlyproducing pressedcracklings from rendered animal matter,such as suet, meat, inedible hard parts and the like.

A further feature of this invention is to provide a product treatmentapparatus which reduces labor requirements and lends itself to anautomated line of product processing.

Still another object of this invention is to provide a liquid expressingpres which is highly efficient and is of rugged, durable construction. I

Further objects as well as features and'advantages of this inventionwill become apparent as the following description of an illustratedembodiment thereof proceeds and is given for the purpose of disclosureand is taken in conjunction with the accompanying drawings in which likecharacter references designate like parts throughout the several viewsand where:

a FIG. 1A is a vertical sectional view through the material receivingend of a liquid expressing press incorporating the principles of thisinvention; 1

FIG. 1B is a similar view showing the discharge portion of said press;

FIGJZ is a fragmentary top plan view forated housing of said press;

FIG. 3 is an elevational view of the conveyors removed from the pressshown in FIG. 1B;

FIG. 4 is a vertical sectional view taken along line 4-4 of FIG. 18looking in the direction indicated by the arrows;

showing the per- FIGJS is a vertical sectional view taken along line 5-5of FIG. 18 looking in the direction indicated by the arrows; and

FIG. 6 is a vertical sectional view taken along line 6-6 of FIG. 13looking in the direction indicated by the arrows.

Referring now to the several figures and first to FIGS. 1A

and 18, a liquid expressing press 11 embodying this invention is held ina generally horizontal position by supports 13. A moisture-containingproduct, such as unpressed cracklings is transferred from a cooker 15 ofa continuous rendering system through a chute 17 into the receiving endof a cylindrical press housing 19. Unpressed cracklings contain amixture of fluids, such as liquefied greases, tallows and lards. Thehousing 19 encloses a screw auger or conveyor 21 which is supported atits outer end by conventional bearings and is rotatable about itshorizontally disposed, longitudinal axis through interconnected gearmeans contained within a gear box 23. A shaft 25 which is operativelyconnected to thegears inside the box 23 carries a pulley 27 on its outerend. The pulley 27 is connected by means such as a chain belt tosuitable drive means (not shown) whereby when the pulley is rotated theauger 21 is rotated.

In the first section of the press 11 the conveyor 21 transportsrelatively small amounts of the unpressed cracklings and liquid greasethrough the housing 19 and into a perforate housing portion 20. Thesmall amounts of cracklings and grease are dragged along by the flightsof the screw conveyor. The perforate portion 20 of the housing shown inFIG. 2 is slotted to provide means of egress for a portion of freeliquid grease to flow or drain away from the unpressed cracklings asthey are moved along through the housing. A drip pan 29 is positionedbelow the perforate portion of the housing 19 to catch the free liquidsflowing out of the press. The conveyor 21 is driven at a constantpredetermined speed which exceeds the flow rate of the material beingdischargedfrom the cooker 15 into the apparatus. The conveyor speed isselected so that the unpressed cracklings are widely distributed andagitated while they are in contact with the perforate portion of thehousing 19. In this way maximum drainage of the liquids from theunpressed cracklings is possible before they are moved into a secondsection of the press where additional liquid is squeezed from the solidmaterial comprising the cracklings.

In the second section of the press, the housing 19 is suitably perforateand encloses a variable pitch, helicoidal screw conveyor 31 which ismounted at its outer end in conventional bearings at 33 for rotationabout its horizontally disposed, longitudinal axis. A shaft 35 extendsfrom the outer end of the conveyor 31 and carries a pulley 37 which iskeyed to the shaft in conventional manner. As the pulley 37. is rotatedby drive means (not shown) the-conveyor is rotated about itslongitudinal axis. The helicoidal flightings 39 are attached to thescrew conveyor 31 so that the pitch between successive flightsprogressively diminishes as the flights approach the outer end of theconveyor 31'. In this way as the cracklings are moved along by theconveyor 31, the area between adjacent flight is successively diminishedand the cracklings are subjected to increased pressure.

As shown in FIGS. 1B and 3 the shaft of conveyor 31 is of a largerdiameter than the shaft of conveyor 21. The inside diameter of thehousing 19 surrounding the conveyors 21 and 31 is constant and thus withthe cross-sectional area of the shaft of the conveyor 31 being largerthan the shaft of the conveyor 21, the space available for thecracklings is reduced in the area of the press containing the conveyor31. In theembodiment shown the helicoidal flightings 39 of the screwconveyor 31 are attached to a cylindrical body portion 41. End rings 43and 44 are attached as by welding, to the ends of the cylindrical body41. A cylindrical tube 46 is mounted coaxially inside of the body 41 andis attached to the end rings 43 and 44. The shaft 35 extends into and isaffixed to the inside wall of the outer end of the cylindrical tube 46so that as the shaft is rotated by its associated drive means, the screwconveyor 31 is rotated. A portion of the shaft 22 of the auger 21extends into the open end of the tube 46 (FIG. 3) and is loosely mountedtherein so as to be rotatable within the tube 46. The tolerance betweenthe outside of the shaft 22 and the inside of the tube 46 and the lengththat the shaft extends into the tube cooperate to align the axis of thescrew conveyors 21 and 31. The shaft 22 and the tube 46 are sufficientlyspaced so that conveyors 21 and 31 can be independently rotated by theirrespective drive means about the single axis extending between thebearings at the outer ends of the conveyors. Thus, the conveyors 21 and31 are operable at different rotational speeds.

As seen in FIG. 3 the cylindrical tube 46 extends a short distancebeyond the end ring 44. A transition portion 48 having an externalsurface in the shape of a frustum of a cone is affixed about theextending portion of the tube 46. The transition portion graduallyincreases the shaft circumference of the conveyor 31 from the outerboundary of the shaft 22 to that of the body 41. Thus as the drainedcracklings are moved from the end of the conveyor 21, they are movedinto and are picked up by the helicoidal flightings 39 of the conveyor31.

Simultaneously the drained cracklings are compressed into a relativelysmaller annular space in the portion of the housing containing theconveyor 31 because the area within the housing 19 occupied by the body41 of conveyor 31 is greater than the area occupied by the shaft 22 ofconveyor 21. Further as hereinabove described the space between adjacentflighting of conveyor 31 is diminished so that as the cracklings aremoved along they are subjected to increased compressive force. Thisstructural arrangement increases the pressure exerted on the cracklingsand forces most of the liquid from the cracklings. By controlling thespeed of the conveyors 21 and 31, it is possible to vary the quantity ofcracklings contained between the flightings of the two conveyors, thedwell time of the cracklings within the influence of the two conveyorsand the compressive forces exerted on the cracklings between theconveyor and the inside of the housing.

As seen in FIG. 4, the cylindrical housing 19 has longitudinal bars 51attached to its inner surface. The bars are spaced around the innercircumference and extend radially inwardly toward the housing axis. Theconveyor 21 is positioned with the housing so that the flight crests ofthe conveyor 21 are spaced a short distance from the surface of the bars51. By being spaced around the inner surface of the housing 19, the bars51 provide an irregular surface over which the cracklings are moved. Asthe screw turns the cracklings being moved along by the flightings passalong and over the irregular surface. This interrupted and discontinuousmotion and agitation increases the tendency of the cracklingsto becomeintermingled so that some of the liquid carried by the cracklings flowstherefrom.

The housing 19 is held in its cylindrical arrangement by a number ofrings 53 which are fixed about the housing along its length. The rings53 hold the housing together and prevent the radial expansion of thehousing due to the pressure exerted by the conveyor on the solids beingpressed.

In FIGS. 5 and 6 the perforate portion of the housing is formed of aseries of ribs 55 which are attached to the inner surface of the rings53. The ribs 55 are spaced to provide substantially radially extendingfluid discharge passages 56 each of which is defined by a pair ofadjacent ribs 55. Ribs 55' extend radially inwardly a preselecteddistance beyond the ribs 55 and are arranged so that each of the ribs55' has at least one of the shorter ribs 55 on-each side. In theembodiment shown each of the relatively long ribs 55' is separated by anumber of shorter ribs 55. The conveyor 31 is positioned within the.perforate portion of the housing 20 that the crests of the flightings 30of the conveyor 31 are spaced a short distance from the ribs 55'. As thecracklings are moved along the perforate portion by the conveyor '31they are moved against the interrupted surface which is provided by theribs 55'. This substantially increases the mixing of the cracklings asthey are being pressed against the ribs and increases the recovery offluid material from the cracklings. The ribs 55 and 55 beinglongitudinally arranged along the length of the housing 19 act as spacedstrainer bars to retain the solid crackling particles within the housingwhile the fluid is being pressed therefrom.

After the compressed and densitied cracklings are moved beyond theflightings 39 they are engaged by breaking bars 57 which extend radiallyoutward from the body 41 of the conveyor 31. The bars 57 have sharpsurfaces which engage the densified cracklings material and break thecracklings into portions of a reduced size which can be conveyed toother apparatus for further processing. The breaking bars 57 rotatewithin a rectangular housing 59 which is open at the bottom fordischarge of the crackling product having a reduced moisture content.

Described briefly the operation of the press is as follows: A quantityof fluid bearing material, such as cracklings is in-' troducedmechanically or manually into the chute 17 which opens into the screwconveyor 21. The screw flights of the conveyor 21 receive the unpressedcracklings and urge them longitudinally through the housing 19. Thematerial is agitated and some pressure may be applied whereby some ofthe fluid is disassociated from the material. The conveyor 21 urges thematerial into the flightings of the conveyor 31 having a shaft which islarger than the conveyor 21 and flightings with diminishing pitch.Because of the difference in shaft size and pitch, increased pressure isapplied on the material as it is moved longitudinally along by conveyor31 through the housing. The conveyors 21 and 31 are independently drivenand their speeds are variable. The speed of the conveyor 31 isrelatively slower than that of the conveyor 21. This further increasesthe compressive forces exerted on the cracklings. By the combinedincrease in shaft diameter, decrease in pitch between flightings, andthe relatively slower rotational speed of the conveyor 31, steadilyincreasing pressure is applied to the cracklings until the majority ofthe fluid is expressed therefrom. Because the perforate portion of thehousing is provided with substantiallyxradially extending fluiddischarge passages each of which is defined between adjacent ribs, thefluid expressed from the material passes easily from the press and iscollected in the drip pan 29. Some of the ribs 55 extend radiallyinwardly beyond the ribs 55'to provide interrupted damming of thematerial being moved through the press. This reduces the tendency of thematerial to rotate with the conveyor and increases the efficiency of thepress and forces a higher proportion of the contained fluid from thematerial. The bars 57 break up the densitied materials coming from theconveyor so that the material can be easily moved from the press forfurther processing.

Thus, it will be appreciated that all of the recited objects, advantagesand features of this invention have been demonstrated as obtainable in ahighly practical apparatus and one that is simple and positive inoperation. 'It will be further un derstood that although this inventionhas been described with respect to certain specific embodiments thereof,this invention is not limited thereto, since various modifications ofsaid invention will suggest themselves to those skilled in the art fromthe aforesaid description and are intended to be encompassed within thescope of the appended claims wherein there is claimed:

lclaim:

l. A press for fluid removal from a mixture of fluids and solidscomprising: a cylindrical housing having an inlet for admitting themixture and an outlet for discharging densified portions of the mixture,at least a portion of the housing wall being perforate to conduct thefluids from the housing and to block passage of the solids from thehousing; a first rotatable screw conveyor mounted in the housing toreceive the mixture and advance the mixture into the housing in contactwith the perforate wall of the housing for draininga portion of thefluid from the mixture; first means for rotating the first conveyor at aselected variable speed; a second rotatable screw conveyor mounted inthe housing adjacent the first conveyor and having helicoidal screwflights, said second conveyor being adapted and arranged to advance themixture from the first conveyor toward the outlet and to compress themixture against the perforate wall; and second means for rotating thesecond conveyor at a different selected variable speed to retard theadvance of the mixture and effect controlled compression of the mixture.

2. The press as claimed in claim 1 wherein the shaft diameter of thesecond conveyor is substantially greater than the shaft diameter of thefirst conveyor.

3. The press as claimed in claim 1 wherein the pitch of the helicoidalflights progressively decreases along said second conveyor in thedirection of the movement of the mixture.

4. The press as claimed in claim 3 wherein the shaft of the secondconveyor isof a larger diameter than the diameter of the shaft of thefirst conveyor, said helicoidal screw flights having decreasing pitchand the larger diameter of the second shaft subjecting the mixture toincreasing pressures as the mixture is moved along the second shafiwhereby still more fluid is pressed from the mixture.

5. The press as claimed in claim 4 wherein the first means is rotated ata speed in excess of mixture flow into the inlet for widely distributingand agitating the mixture being advanced by the first conveyor.

6. The press as claimed in claim 5 wherein a first annul space isdefined between the housing and the shaft of the first conveyor, thefirst annular space being of an area four times greater than the area ofa second annular space defined between the housing and the shaft of thesecond conveyor.

7. The press as claimed in claim 6 wherein the second shaft furthercomprises a nonuniform section in the form of a frustum of a cone withthe smaller end of-the frustum adjacent the first shaft.

8. The press as claimed in claim 7 wherein the second conveyor furthercomprises means for successively shearing off fragments of the densifiedmixture and for moving the fragments from the discharge opening.

9. The press as claimed in claim 8 wherein the shearing means comprisesa plurality of angularly disposed blade mem bers.

10. The press as claimed in claim 9 wherein the housing comprises aplurality of longitudinally arranged strainer bars, adjacent ones ofsaid bars being spaced from each other.

